A retrospective review of the multidisciplinary management of medullary thyroid cancer: Eligibility for systemic therapy

Abstract

Background: Medullary thyroid carcinoma (MTC) accounts for 1-2% of all thyroid cancers. The clinical course of metastatic disease can be indolent. Our aim was to characterize the natural history of disease to evaluate the true proportion of patients who would be eligible for the currently available systemic therapies. Methods: The British Columbia Cancer Agency (BCCA) provides cancer care to a population of 4.6 million. A retrospective chart review was conducted of all patients with MTC referred to the BCCA from 1991 to 2013. Clinical characteristics, pathology, treatment and outcome data were collected. Relapse free survival and overall survival was determined for patients based on staging at the time of diagnosis. Results: Of the 98 patients referred to the BCCA during the study period, inherited mutations were found in 6% though 60% did not undergo genetic testing. Based on clinical SEER staging at diagnosis 50% had localized disease, 38% regional, and 12% had distant metastasis. 77% had complete surgical resection of which 25% received adjuvant radiation therapy. Five year relapse free survival (RFS) for localized and regional disease was 75% and 66%, respectively (p = 0.006). Initial treatment of 23 patients with locally unresectable and metastatic disease predominantly involved multiple modalities. Of the 37 patients with relapsed or metastatic MTC only 7 (19%) patients received one or more course of chemotherapy for metastatic disease: 1 temsirolimus, 2 adriamycin, 3 sunitinib, 3 sorafenib, and 3 vandetanib. Five year OS based on clinical SEER stage: localized 93%, regional 72% and distant 33% (p < 0.001). Conclusion: Localized and regional MTC treatment patterns reflect multidisciplinary management based on disease characteristics. Patients with distant disease had poor outcomes with 28% of patients dying from disease. In our cohort the minority of patients ultimately received systemic therapy due to timing and lack of TKI availability.